1. Field of the Invention
The present invention relates to a switching device for controlling the supply of electric power from a power supply to a load. More particularly, the present invention relates to a switching device for controlling a rush current at the time of starting or stopping the driving of the load.
The present application is based on Japanese Patent Applications Nos. Hei. 11-49887 and 2000-16804, which are incorporated herein by reference.
2. Description of the Related Art
A switching device is used for controlling the supply of electric power from a power supply to each load in, for example, an automobile, and is comprised of a semiconductor switch for effecting a changeover between the supply and cutoff of electric power, a controlling device for effecting on/off control of the semiconductor switch, etc. In such a switching device, when the semiconductor switch is turned on and the current begins to flow, there are cases where a rush current which is larger than the normal current necessary for driving the load occurs in the manner of a pulse. This rush current constitutes causes of faults in the load such as by generating noise and shortening the service life.
To suppress such a rush current, the related switching device employs a controlling device such as a microcomputer to effect the duty control of the drive signal waveform during the starting and stopping of the load driving.
With the above-described switching circuit, however, the microcomputer and the like become necessary as the controlling device for suppressing the rush current, so that there is a problem in that the device becomes complex.